12v alternator wind turbine with gearbox

i have been wanting to experiment with wind power for a future off grid move to south dakota.
i often hear that automotive 12v alternators will not work well because they need to be spun much faster than a standard wind turbine is capable of safely spinning... but the only real reasons i have heard for not using a gearbox to solve this porblem is that they are too ugly or too much of a draw on the turbine to be practical.. which may be true for a small diameter wind turbine with 3 blades designed to spin a generator at a few hundred rpm.. but the old school multi bladed turbines you see on ranches etc have the torque to spin well water pumps so i dont see how a small gearbox can cause enough resistance to bog down a application designed turbine..
VERY basic drawing explaining what i am thinking of for a design
this is not to scale or exact to design it is just a basic layouthttp://i177.photobucket.com/albums/w216/ridered972/windturbine.png

using only basic cheap parts... several sealed bearing 14mm axle bicycle hubs with 9t drivers (common size on modern bmx bikes)... and 44t sprockets (common on older and low quality and race bmx bikes)... some steel to weld up a frame to mount the hubs to... spare chain sections and some time welding and would it not work to spin an alternator at a resonable speed?
as i added it up with an input speed of only 100rpm from a 10'+ wind turbine with multiple blades for more torque less speed... after only 3 gear ups would be spinning 6500 rpm which is well above the minimum speed to make full power from an automotive alternator.. granted bicycle hubs are not designed for this speed but bearings and hubs can be upgraded to pipe and bearings that can handle the stress
would also be very easy to add multiple alternators to the final drive sprocket to multiply power

am i on a resonably accurate track here or is there something a completely overlooked??
i like the use of an alternator because they are readily available.. cheap... designed to run for a long time.. internal and externally regulated options... and a huge range of amperages to choose from for system tunibility

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Comments

I think you will find most here are pretty down on small scale wind. The reality is if you have enough wind to be useful (more thn 12 mph AVERAGE!) you have too much for the hardware to be reliable. You must realize that small scale wind machines live in harsh environments, with lots of moving parts, lots of live loads, living high off the ground making service difficult.
The world is littered with small scale wind machines that have been tossed on the junk heap becaus ether fail to deliver thier promise, and they don't last very long. even our site sponser generally eschews small scale wind in general.

In the real world, in SD PV is gng to give you way more ban for your buck, and will be way more reliable.

All that said, play around and see how it works, but understnd that there is VERY little power in the wind below 12 mph, even if the blades spin. A steady 15 mph wind makes you hang on to your hat, and gets old real quick!
welcome to the forum, and fee free to ask as many questions as you wish, and folks here will try to answer them as best we can, even profer an opinion now and again.

i have been wanting to experiment with wind power for a future off grid move to south dakota.
i often hear that automotive 12v alternators will not work well because they need to be spun much faster than a standard wind turbine is capable of safely spinning... but the only real reasons i have heard for not using a gearbox to solve this porblem is that they are too ugly or too much of a draw on the turbine to be practical.. which may be true for a small diameter wind turbine with 3 blades designed to spin a generator at a few hundred rpm.. but the old school multi bladed turbines you see on ranches etc have the torque to spin well water pumps so i dont see how a small gearbox can cause enough resistance to bog down a application designed turbine..
VERY basic drawing explaining what i am thinking of for a design
this is not to scale or exact to design it is just a basic layouthttp://i177.photobucket.com/albums/w216/ridered972/windturbine.png

using only basic cheap parts... several sealed bearing 14mm axle bicycle hubs with 9t drivers (common size on modern bmx bikes)... and 44t sprockets (common on older and low quality and race bmx bikes)... some steel to weld up a frame to mount the hubs to... spare chain sections and some time welding and would it not work to spin an alternator at a resonable speed?
as i added it up with an input speed of only 100rpm from a 10'+ wind turbine with multiple blades for more torque less speed... after only 3 gear ups would be spinning 6500 rpm which is well above the minimum speed to make full power from an automotive alternator.. granted bicycle hubs are not designed for this speed but bearings and hubs can be upgraded to pipe and bearings that can handle the stress
would also be very easy to add multiple alternators to the final drive sprocket to multiply power

am i on a resonably accurate track here or is there something a completely overlooked??
i like the use of an alternator because they are readily available.. cheap... designed to run for a long time.. internal and externally regulated options... and a huge range of amperages to choose from for system tunibility

Hi jblob,

I will limit myself to a few comments and leave some room for others.

1. The windmills that I have seen on ranches do not spin pumps at all, they lift and lower a pump rod for a piston pump inside the well. So speed is not important in getting the pump to work. The faster the windmill spins, the faster the water comes out, but the force required does not change.

2. The problem with a gearbox is not "bogging down" it is inefficiency. A ranch windmill has power to spare, since the water can be pumped over a period of time and stored. A wind turbine can only capture a certain amount of power from the wind and you would like as much as possible to be converted to electrical energy. So a gearbox which has 90% efficiency will be costing you 10% of your available wind energy. (Also, I believe that it is harder to build efficient gearboxes to increase speed than it is to decrease speed. Comments on that?)

3. The bicycle chain, when kept clean and lubricated properly is an amazingly efficient way of transferring energy. Under optimal circumstances, efficiencies of over 98% have been measured. You will not see that in a gearbox.Even at higher gear ratios and with a lateral offset between sprockets it is typically over 80%. But exposed chains get dirty fast, lose efficiency and start an accelerated pattern of wear. Especially in wind borne dust.

thank you both for the quick replies.
that does make more sense i couldnt figure out why gearing up would be so difficult.
as far as gearing up vs gearing down it would take less rotating energy to gear speed down and would increase the output torque like 1st gear vs 4th gear in a car.. 1st is slower but lot of torque... 4th is fast but low amount of torque but it would take less energy to gear up by speed with a few gears vs one larger one.. would cause more loss in efficency from bearings chains etc but would take less torque to spin it up.. goes back to school learning about simple machines :roll: multiple gears make it take less force to increase ratio but using inefficent gearing and drive systems would take away from the advant.... this is all by observation cant say this is fact but from experience in other things like changing bike gearing it makes sense to me

http://i177.photobucket.com/albums/w216/ridered972/map2-1.gif
i found a wind speed map and the area im looking at moving to is marked at an average wind speed of 13.4 mph or so at 30' above ground level. designing a turbine around average of 13mph and with an average of 3.5kw/h thru the day power usage i will need somewhere in the range of 5kw of power generation to keep from depleting the battery bank in low winds and cloudy days... want only minimal usage of a backup generator..

anyone have experience with making solar panels from the cell packs on ebay? not the largely broken cells but a and b grade cells with only rough edges and chips? they seem to be a great value compared to buying premade panels.. im not worried about hetting shoulder deep in a project as long as i can get it done and not end up having another junkpile project like so many have lately

also i didnt realize how the water pumps worked on the windmills.. that makes more sense than turning a typical pump.. similar to the classic oil pumping rigs you see off the highway..

I agree that an automotive alternator is not a good wind generator--They need to spin around 6,000 RPM for maximum power. I have used about 50% for losses with a speed increasing transmission (don't know if correct or not).

There are permanent magnet "conversions" and new construction (PMA--Permanent Magnet Alternators). The three forums/sources above (repeated below) are very good for DIY and other wind power questions:

Small wind is difficult to have it work well (produce power) and last a long time. Sticking a 60' tall tower in rain/wind/sun/lightning and from zero to 100+ MPH winds--is difficult to do "cheap" (i.e., cost effectively).

We have one user that is very happy with his Windmax. And our host is trying out TLG (customers seem to be happy).

In the end you need to live in a pretty windy area to get "useful" amounts of wind power ("flagging" trees). 300-500+ feet way from obstructions, 30 feet above local obstructions, and 60 foot minimum tower height... At least as a start.

When you see turbines mounted to homes, roof peaks, next to tall buildings, etc... Assume they are there for art work and not to really generate useful power.

-Bill

From the same post above:

Here is a good series on Do It Yourself solar panel construction (don't recommend, but if you want to try--added Aug 7th, 2011):

Note--It is very difficult to build reliable and "fire resistant" panels that will last more than a few months in weather/sun/etc... Also, remember the cells you are buying are, most likely, rejects from solar panel firms.

As for "making your own" PV, we have people asking all the time, and almost no one, (perhaps no one ever!) has had any real long term success doing is. with new manufactured PV under $1/watt from some venders, and certainly under $2/watt in many places why in the world would you want to build your own?

3.5 kwh of power can easily (battery based) come from ~ 1800 watts of PV using my rating plate/2*4 rule. That is ~$3500 worth of PV. what is it going to cost you to build panels, and how reliable are they going to be? How mu ch is it gng to cost you to build the equivalent of small scale wind and how reliable is it going to be? For my money, it is no contest,, buy new PV, good charge controller, (for that kind of loading you really have to consider 24 or 48 vdc system) a good battery bank and you will be happy. Anything less and you re going to be disappointed.

thank you for te links that will help a lot in qorking out what system will work out best. a PMA would be useful. and the area im looking at is about as wind friendly as i have found... almost no trees only small ones far between, pretty flat with small rolling hills no houses or anything nearby to disturb the wind. a bigger turbine that can put out 3+kw would be ideal but would also be bigger and harder to get up and down for maintenance.. possibly a guywire system to lower it on a pin base and lean over to the ground.
will spend a while browsing those links and see what i can find

As for "making your own" PV, we have people asking all the time, and almost no one, (perhaps no one ever!) has had any real long term success doing is. with new manufactured PV under $1/watt from some venders, and certainly under $2/watt in many places why in the world would you want to build your own?

3.5 kwh of power can easily (battery based) come from ~ 1800 watts of PV using my rating plate/2*4 rule. That is ~$3500 worth of PV. what is it going to cost you to build panels, and how reliable are they going to be? How mu ch is it gng to cost you to build the equivalent of small scale wind and how reliable is it going to be? For my money, it is no contest,, buy new PV, good charge controller, (for that kind of loading you really have to consider 24 or 48 vdc system) a good battery bank and you will be happy. Anything less and you re going to be disappointed.

Tony

i have thought a 24v system would be better for the power level to lower the amperage. if not worth the effort i wont waste the money and time to make my own pv panels. 2kw worth of panels a 24v battery bank and two or three well suited turbines would be about all i need.. wont have to heat and cool the house so that helps..
thank everyone for the info and the links will do some research on systems inverters etc and get a better plan ironed out.. have two years before the move but this isnt exactly a small investment

The utility scale sized wind turbine companys are trying to design new turbines without gearboxes. I worked at a foundry that was making castings for the wind industry. Before I retired the President of the foundry let me view some of the new castings they were going to bid on. The gearboxes are the weak part of present turbines. Most turbines wear out 2 gearboxes in thier designed life. I wouldn,t recomend gearboxes for a small turbine. Has anyone seen any new large turbines without gearboxes yet? I think it might be Siemens that wanted to make a utility sized PMA wind turbine. :Dsolarvic:D

anyone have experience with making solar panels from the cell packs on ebay? not the largely broken cells but a and b grade cells with only rough edges and chips? they seem to be a great value compared to buying premade panels..

For small "just for fun" projects they are OK, I guess, but if you are wanting to build anything with any practical use, get manufactured modules.

not going to waste the time and money on making my own panels when they can be had for $1.20 a watt any day of the week :
did some more research on battery banks pv panels turbines etc...
thankfully i picked an area that has both good wind and solar resources to take advantage ofhttp://i177.photobucket.com/albums/w216/ridered972/us-map-of-photovoltaic-solar-resource.jpg
approx 5kw per square meter solar resource (not factoring panel efficency of MUCH less)http://i177.photobucket.com/albums/w216/ridered972/map2-1.gif
and average of 12.5/13.5mph wind speed
have been reading thru otherpower.com a lot and somewhere between their 10' and 17' turbine is about where i need to be maybe 12' or 14'. batteries are awfully spendy but an off grid system is the only option and would be worth it over time anyway.
planning to convert a spare 1.8L isuzu engine from my luv to spin a generator head for backup power.. can throw a small 1 barrel on it and run it down low to spin a 5-10kw generator head

Using PV Watts for Rapid City S.D., fixed array, tilted to 44 degrees from Horizontal (may need near vertical for winter if significant snows in your area--both self clearing and lots more power with reflection from snow):

Using an Isuzu gasoline motor like that would be a huge waste of fuel.. it will consume about 1 to 1.4 gal per hour. A single cyl 12hp diesel engine will consume about 1 gal in 4 hours.. Look for one that does 1800 rpm not 3600 rpm.

thank everyone for the continued input and information.
the isuzu engine was one of those things i thought about offhand because it is just sitting there.. in stock form has about 80hp @4600rpm but running at 800-1000rpm or so it would be hard pressed to see over 25-30. also thought about a lawn mower or similar engine running a belt to a pair of alternators.. only advantage i saw to a bigger engine/genny is that since it has an electric starter it can be wired up to start at low batt voltage and switch off when the battery bank is at full power to minimize fuel/time waste, and has the torque to spin a large gen head if needed.. they are bulletproof little motors, found a few military surplus 24v generators online the other day that may be the route i go.. anything military surplus has to be built to handle some serious usage

planning to run 24v panels, turbine and battery bank to lower the required amperage and wire thickness to reduce system losses.
thank you bill have been wondering what the usable output would be for pv panels in the area. not for from rapid city either so that will be real accurate for my use
its great to have so many online sources of information without a bunch of salesmen shoving gimmicks down my throat..
still working out the overall system needs for amp/watt hours but as i see it a battery bank is going to be in the ballpark of $2000-3000, panels $2700-$3000 (rather a little overkill than coming up short) and $1000+ to assemble a usable turbine with at least 1kw output @12.5mph wind average.. $6200-7000 for 10-15 years of sustainable power that isnt too bad.. average power bill around my current house would be considerably higher over that much time.

i see a ton of the huge turbine blades coming down the freeway on trucks on my way home from work in the mornings and those things are scary big... even at 50rpm they would be terrifying to be near.. but the design of them is almost exactly the same as i see on otherpower.com builds so at least i know i have a good source of information for building my own.. anyone who hasnt taken the time to go thru their site needs to do so... tons of information, builds step by step and system design tips..

also thought about a lawn mower or similar engine running a belt to a pair of alternators.. only advantage i saw to a bigger engine/genny is that since it has an electric starter it can be wired up to start at low batt voltage and switch off when the battery bank is at full power to minimize fuel/time waste, and has the torque to spin a large gen head if needed.. they are bulletproof little motors, found a few military surplus 24v generators online the other day that may be the route i go.. anything military surplus has to be built to handle some serious usage

A lawnmower engine, like a 3600 RPM portable generator engine, is not intended for long term use either in terms of run time per use or total hours without major maintenance. It would be more suitable for emergency use or battery equalization than for regular frequent use.

if i was going to use a small engine it would end up being something like a small honda 1 cyclinder.. i had a little honda z50 back when i was little and that thing was bulletproof... i am sure it would have outlived pretty much anything i have owned since. and they are one of the most common engines ever made so i can find one anywhere. mainly i would just be using one to keep the battery bank form getting too low on voltage and not for continuous power generation.. between solar and wind it shouldnt need to be run often.